Can I set render settings by individual scenes?
Yes you can, make sure when creating a new scene to choose New for a fresh default scene or Full Copy to make a copy of your current one.

Any changes you make to the settings in either scene will stay unique to that scene.

As per the wiki, the three options when creating a new scene that I think you should pay attention to are:


  New
  Creates an empty Scene. In the new Scene, the Render Settings are set to the default values.
  
  Copy Settings
  Creates an empty Scene like the previous option but also copies the Render Settings from the original Scene into the new
  one.
  
  Full Copy  Is the deepest form of copying available. Nothing is shared. This option creates a fully independent Scene with copies of
  the currently selected Scene's contents. Every Object in the original
  Scene is duplicated, and a duplicate, private copy of its ObData is
  made as well.